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default flow entries installed by ODL when switches get connected

asked 2015-10-05 05:29:33 -0700

anonymous user


Hi Experts, Can you please tell me for what purpose ODL installs default flows when switches get connected. Below are the flow entries in each switch. (My config is sw2---sw1---sw3) | | | | h1 h2 h3 h4

0419:~/Downloads/distribution-karaf-0.3.1-Lithium-SR1$ sudo ovs-ofctl dump-flows s1 -O Openflow13 OFPSTFLOW reply (OF1.3) (xid=0x2): cookie=0x2b00000000000047, duration=6.931s, table=0, npackets=40, nbytes=7342, priority=0 actions=drop cookie=0x2b00000000000047, duration=0.957s, table=0, npackets=1, nbytes=315, priority=2,inport=1 actions=output:2 cookie=0x2b00000000000046, duration=0.957s, table=0, npackets=1, nbytes=315, priority=2,inport=2 actions=output:1 cookie=0x2b00000000000047, duration=6.926s, table=0, npackets=4, nbytes=340, priority=100,dltype=0x88cc actions=CONTROLLER:65535

0419:~/Downloads/distribution-karaf-0.3.1-Lithium-SR1$ tel@tel-CHN-0419:~/Downloads/distribution-karaf-0.3.1-Lithium-SR1$ tel@tel-CHN-0419:~/Downloads/distribution-karaf-0.3.1-Lithium-SR1$ tel@tel-CHN-0419:~/Downloads/distribution-karaf-0.3.1-Lithium-SR1$ sudo ovs-ofctl dump-flows s2 -O Openflow13 OFPSTFLOW reply (OF1.3) (xid=0x2): cookie=0x2b00000000000046, duration=11.053s, table=0, npackets=31, nbytes=4569, priority=0 actions=drop cookie=0x2b00000000000041, duration=5.076s, table=0, npackets=10, nbytes=1808, priority=2,inport=3 actions=output:2,output:1 cookie=0x2b00000000000042, duration=5.076s, table=0, npackets=1, nbytes=70, priority=2,inport=1 actions=output:2,output:3,CONTROLLER:65535 cookie=0x2b00000000000040, duration=5.076s, table=0, npackets=1, nbytes=70, priority=2,inport=2 actions=output:3,output:1,CONTROLLER:65535 cookie=0x2b00000000000045, duration=11.058s, table=0, npackets=3, nbytes=255, priority=100,dl_type=0x88cc actions=CONTROLLER:65535

0419:~/Downloads/distribution-karaf-0.3.1-Lithium-SR1$ sudo ovs-ofctl dump-flows s3 -O Openflow13 OFPSTFLOW reply (OF1.3) (xid=0x2): cookie=0x2b00000000000043, duration=13.958s, table=0, npackets=33, nbytes=4962, priority=0 actions=drop cookie=0x2b00000000000045, duration=7.970s, table=0, npackets=9, nbytes=1493, priority=2,inport=3 actions=output:2,output:1 cookie=0x2b00000000000044, duration=7.970s, table=0, npackets=1, nbytes=70, priority=2,inport=1 actions=output:2,output:3,CONTROLLER:65535 cookie=0x2b00000000000043, duration=7.970s, table=0, npackets=1, nbytes=70, priority=2,inport=2 actions=output:1,output:3,CONTROLLER:65535 cookie=0x2b00000000000043, duration=13.970s, table=0, npackets=3, nbytes=255, priority=100,dl_type=0x88cc actions=CONTROLLER:65535 tel@tel-CHN-0419:~/Downloads/distribution-karaf-0.3.1-Lithium-SR1$

Also when i try to ping from h1 to h4 packetin msg is reaching the controller, but no flow mod is installing for that paketin, also ping is successful.

My questions,

  1. what happen to that packetin? (lot of packetin msg are reaching the controller but no response from controller side)
  2. In the flow entry above packets are flooding to all the other port expect in_port, wht is the reason to install a flow like that?

Note: Used Mininet to create the topo and used ... (more)

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2 answers

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answered 2015-10-05 22:02:49 -0700

Ashwini_Mhatre gravatar image

Hi, in general in opendaylight l2switch project responsible for adding flow entries. U can go through its code.

Regards, Ashwini mhatre.

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Hi Ashwini, I do not think l2switch module is installing the flow entires, only openflowplugin module is installing. I just uninstalled the l2switch module even then default flow entries are getting installed by openflowplugin module.Please refer this link also for your refrence

senthil_tata ( 2015-10-14 23:44:09 -0700 )edit

answered 2015-10-06 08:46:41 -0700

jamoluhrsen gravatar image

The flows you have in your switches are punting LLDP (dltype 0x88cc) to the controller. Those are probably the packetins you are seeing. Those are what ODL will use to learn the links in the network. It will be sending down packetout LLDP messages on one switch port and then the connected switch will punt it to the controller (note: that flow has highest priority=100). When the controller gets that packetin from the LLDP it has sent as a packet_out, it will know there is a link there.

The other flows are doing like you say and just blindly forwarding like this:

s1  :  in_port:1 --> forward out port 2
       in_port:2 --> forward out port 1

s2  :  in_port:3 --> forward out port 1 and 2
       in_port:1 --> forward out port 2 and 3
       in_port:2 --> forward out port 3 and 1

s3 (same as s2)

Assuming you have L2-switch installed those forwarding rules should be loop free, but also allowing full connectivity between end hosts.

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First Thanks a ton for your comment. I understand about LLDP packetins, but my question is packetin msg about pinging from h1 to h4 as the rule below (you have not mentioned the output CONTROLLER:65535). The exact rule is s2 : in_port:3 --> forward out port 1 and 2 in_port:1 --> forward out port 2 and 3 and CONTROLLER:65535 in_port:2 --> forward out port 3 and 1 and CONTROLLER:65535 My concern is about packetins when i do ping (h1---h4), as per the rule the packet is going to controller also, so for that packetin there is no packet out and no flow-mod is got installed, the ping is happening as it sends to all the ports in the switches. Thanks in Advance!!!!

senthil_tata ( 2015-10-07 02:59:42 -0700 )edit
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Asked: 2015-10-05 05:29:33 -0700

Seen: 1,299 times

Last updated: Oct 06 '15